The invention concerns an internal gear pump with an internal gear, a thrust plate arranged on each of the two sides of the internal gear, a powered external pinion of eccentric arrangement relative to the internal gear and meshing with it, and a sickle-shaped floating filler part split in peripheral direction. The sickle-shaped floating filler part bears with its blunt end on an axial support pin while its first segment, facing the teeth of the pinion, has a greater radial thickness than its second segment facing the teeth of the internal gear. The first segment features in the parting surface at least one axially extending groove for accommodating a sealing element.
An internal gear pump of the type described above is known in DE-OS 26 06 082 and DE-OS 25 33 646.
In this prior internal gear pump, the filler part is in peripheral direction split in two segments so that the two segments, due to the pressure prevailing between them, will be forced separately on the tooth heads of the coordinated gears, thereby enabling a compensation for the radial positional shift of pinion and internal gear in contingence on pressure, speed of rotation and viscosity.
The contact force of the tooth heads is so dimensioned that at normal operating conditions there occurs no wear on the filler parts. In practice, however, it has been demonstrated that at extreme operating conditions, for instance with heavily polluted oil or air bubbles contained in it, the conditions of force are altered primarily on the segment facing the pinion, so that this segment endures heavy wear, which eventually leads to breakage of the segment and, thus, total failure of the pump.
Therefore, the problem underlying the invention is to restrict the wear on the first segment facing the pinion, in order to prevent breakage and thus total failure of the pump.